The probe will fly through the corona of the Sun
The launch of a probe to get closer to the sun than ever before has been delayed.
The Parker Solar Probe was due to launch from Cape Canaveral in Florida on Saturday morning.
However NASA says this was was scrubbed due to a "violation of a launch limit".
"There was not enough time remaining in the window to recycle", it says.
The launch is planned for Sunday, which will have a 60% chance of favourable weather conditions.
NASA's Parker Solar Probe will provide unprecedented information about the Sun, where changing conditions can spread out into the solar system to affect Earth.
The spacecraft is due to fly directly into the Sun's atmosphere where, from a distance of some four million miles from its surface, the spacecraft will trace how energy and heat move through it.
It will also explore what accelerates the solar wind and solar energetic particles.
Temperatures in the corona - the outermost layer of the solar atmosphere - spike upwards of one million degrees Celsius.
While just 1,000 miles below, the underlying surface simmers at a balmy 5,000 degrees.
The spacecraft and its instruments will be protected from the heat by a 4.5-inch-thick carbon-composite shield.
This will need to withstand temperatures outside the spacecraft that reach nearly 1,377 degrees Celsius.
How the Sun manages this feat remains one of the greatest unanswered questions in astrophysics.
The Parker Solar Probe will fly through the corona itself, seeking clues to its behaviour and offering the chance for scientists to solve this mystery.
The probe will use Venus’ gravity during seven flybys over nearly seven years to gradually bring its orbit closer to the Sun.
The spacecraft will fly through the Sun’s atmosphere as close as 3.8 million miles to the star’s surface, well within the orbit of Mercury and more than seven times closer than any spacecraft has come before.